ANXIOUS ministers have forced the postponement until after the local elections of a confrontation between the Government and local authorities over the nuclear industry's plans to dispose of radioactive waste deep underground near Sellafield in Cumbria.

UK Nirex, the industry's waste management company, has drawn up plans for the first stage of its waste repository and wants planning permission from Cumbria County Council. But the Department of the Environment is resisting the council's demands for a full public inquiry into nuclear waste disposal.

The conflict will come out into the open once Nirex submits a formal planning application. But at an international conference on nuclear reprocessing and waste disposal held in London last week, informed sources said that ministers had virtually instructed Sir Richard Morris, the chairman of UK Nirex, to put off any application. So politically sensitive is the issue that it may have to be postponed again until the European elections are out of the way in June.

Nirex has drawn up plans for a pounds 200m subterranean laboratory to test the properties of the 'Borrowdale Volcanic Group' of rocks 650 to 800 metres underground where it intends to put the nuclear waste. The county council sees the laboratory as something of a Trojan Horse: once permission is granted for the excavation of the laboratory, the nuclear industry will be so committed to the Sellafield site that, for all practical purposes, it could never retract.

According to internal documents which have come into the hands of the Independent, the company maintains that the laboratory - which it styles a 'rock characterisation facility' (RCF) - 'is designed for investigatory and experimental purposes and, as a matter of law, the planning permission for the RCF would not allow its use for other purposes'. But the council believes a public inquiry must be held into the whole issue of nuclear waste policy because the laboratory 'is not just a super borehole but represents a major construction exercise, with the sinking of two shafts, the opening up of caverns and a 10-year programme of testing and development'.

Nirex hopes to have its repository in operation by about 2010 and some observers believe the timetable is so tight that the company will be forced to use the shafts sunk for the RCF for fast access to excavate the repository itself. The time-critical part is the underground cavern where the waste packages will be received and processed, because this is the area where strict precautions will have to be taken to limit radiation doses to the operators.

The county council has been pressing for an inquiry which would examine why Sellafield was selected as Nirex's preferred site in the first place. The industry believes that waste disposal policy was laid down by the late Nicholas Ridley, when he was Secretary of State for Environment, and that it need do no more than justify its choice of Sellafield rather than Dounreay in the north of Scotland.

However, Nirex effectively reversed government policy in a little- noticed announcement early last month. In his statement on 1 May 1987, Mr Ridley told the Commons that the Government had abandoned the idea of burying low-level waste in near-surface facilities and that low-level and intermediate- level nuclear waste should be buried together in a deep underground repository. But Nirex announced that almost all low-level waste for the foreseeable future would be buried in near-surface facilities at Drigg, near Sellafield, and only plutonium-contaminated material would be consigned to the underground repository.